UNDERSTANDING ISO ON THE UNDERGROUND #ShootManualLDN


We Brits love our manual cars. Automatic you say? Most of us would scoff at this notion. Shifting a gearstick is just plain marvellous and we wouldn't give it up without good reason... 



So if you've forked out for a fancy camera, why would you want to use it in auto mode? If you've been following Shoot Manual LDN for a while now, you'll know that my biggest aim is to help you take creative control of your camera and switch from auto to manual mode. This might seem daunting at first but with a few basics under your belt, you'll be flying in no time.  One of the first things you'll need to understand is the exposure triangle. If you are still a bit unsure about what this is, check out my post here.

To get your manual exposure sorted, you need to think about your aperture and shutter speed settings. The third and final piece of the puzzle is ISO.


What is ISO? (pronounced eye-so)


I'll be honest, for me, ISO is probably the least fun of the three corners of the triangle of exposure. The good news is that I've always found ISO to be the easiest setting to understand.

Simply put, ISO refers to your camera's sensitivity to light. The lower your ISO number, the less sensitive your camera is to the light, whereas a higher ISO number increases your camera's sensitivity to light.

ISO might not be the most exciting setting (sorry ISO) but it IS useful because it can often help you get away with not using a flash. When you know what aperture and shutter speed settings you want to use, ISO is the last piece of the puzzle in terms of getting a properly exposed photo.


How do I know what ISO setting to choose?


For me, a general guide I like to keep in mind looks a little like this:

Outside, bright sunny day = low ISO like 100 or 200
Bright but cloudy day = 400 or 800
Indoors but not too dark = 1000
Indoors with low light = high ISO like 1600 

A high ISO is great for helping you steer clear of using your pop up flash but it does bring "noise" or grain to your photo. It's not that pretty, especially on skin tones, so ideally, you want to try to keep your ISO as low as you can whilst still balancing it with your aperture and shutter speed. Remember we talked about balancing your settings here

The London underground has some pretty tricky lighting conditions so it's a good place to experiment with your ISO setting.

For this first shot, I just wanted to capture the scene and I wasn't worried about using a high ISO even though it would mean a bit of grain.

f4     1/400     ISO: 5000

This is what noise/grain looks like up close.



Grain isn't pretty, but without using a high ISO down in this dim light, there's no way I could have:
        
          -Used a fast shutter speed to freeze the commuters on the escalator
          -Handheld my camera (dreaded "camera shake" would have reared its ugly head)

For this next shot, I wanted to try to keep my photo as free from grain as possible. With this dim lighting, there had to be a trade off. To keep my ISO low, I opted for a slow shutter speed. This meant I had to pop my camera on something rather than hold it myself, to avoid the dreaded camera shake.

f5     0.5     ISO: 100

Bingo! Low ISO and less grain. As an added bonus, I actually quite like the motion blur in this shot. Having the freedom to play around with your settings like this is exactly why manual mode is so much fun! 

Pro tip: In the right circumstances noise/grain can actually look pretty good. In fact, I think it lends itself well to a moody black and white photo. Some photographers like the brilliant Jeff Ascough will actually use editing software to add more grain rather than reduce it. 

So what do you think about noise/grain in a photo? Like it or loathe it? Let me know in the comments below, I'd love to hear from you. 

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